I'm not sure what the presence of a map on Heathrow's website actually proves, if anything. It would be very surprising if you weren't able to find maps of all 3 of the Davies Commission's shortlisted options on the Net.
The NW option is the one favoured by Heathrow Airport, so it would be very strange if there were no details of it on their own website.
Ditto the shortlisted Heathrow Hub and Gatwick proposals on their respective websites.